In general, the washing machine washes laundry by using friction between washing water and the laundry in a drum rotated by a motor in a state detergent, washing water, and the laundry is introduced into the drum. The drum is a washing tub for holding washing water and the laundry, and applicable to the washing machine, irrespective of the washing machine being of a drum type or a pulsator type.
In the meantime, depending on driving types of the washing machine, there are indirect coupling type in which driving power is transmitted from the motor to the drum indirectly through a belt wound around a motor pulley and a drum pulley, and a direct coupling type in which the motor is directly coupled to the drum, to transmit driving power from the motor to the drum, directly.
The type of washing machine in which driving power is transmitted from the motor to the drum indirectly through a belt wound around a motor pulley and a drum pulley causes an energy loss in a course of the driving power transmission, and generates much noise in the power transmission course. Consequently, in order to solve such problems, it is a recent trend that use of washing machines having the direct coupling drum type motors applied thereto increases.
FIGS. 1 and 2 illustrate sections showing a related art drum type washing machine and a motor, respectively.
Referring to FIG. 1, there is a tub 2 in a cabinet 1, with a drum 3 rotatably mounted on a center of an inside of the tub 2.
At a rear of the tub 2, there is a motor having a stator 6 and a rotor 5, wherein the stator 6 is fixedly secured to a rear wall of the tub, and the rotor 5 surrounds the stator 6, and is fixed to a shaft 4 that passes through the tub and is connected to the drum 3. Though not shown in detail, on an inside surface of the rotor 5, there are magnets of opposite poles arranged alternately.
Together with this, it is preferable that there is a metal tub supporter (not shown) between the tub rear wall and the stator, having a shape in conformity with an exterior shape of the rear wall of the tub 2, to be fixedly secured to the rear wall of the tub at the time the stator is secured, for supporting a weight of the stator, and maintaining concentricity of the stator.
In the meantime, there is a door 7 on a front of the cabinet 1, with a gasket 8 between the door 7 and the tub 2.
There are hanging springs 9a between an inside of an upper side of the cabinet 1 and an upper side of an outside circumference of the tub 2, for supporting the tub 2, and friction dampers 9b between an inside of a lower side of the cabinet 1 and a lower side of an outside circumference of the tub 2.
In the meantime, FIG. 2 illustrates an enlarged sectional view of the motor and a portion having the motor mounted thereon, wherein the related art stator 6 is fixedly secured to a bearing housing ‘B’ fixed to a rear wall of the tub 2, and the rotor 5 is rotatably mounted to an outside of the stator 6. There is a rotating shaft 4 having one end fixed to a center of the rotor 5, and the other end connected to the drum 3 or the like. Mounted on an inside circumferential surface of the rotor 5, there are permanent magnets 5a. The stator 6 has cores and coils each wound around an outside circumference of the core, to function as an electromagnet.
Therefore, upon supply of power to the coil, the rotor rotates by action of a rotating magnetic field between the permanent magnets and the electromagnet, and rotation torque of the rotor 5 is transmitted to the drum 3 or the like through the rotation shaft 4.
In a bottom of a frame of the related art rotor, there are holes 5b for passing through of external air to cool down heat generated at the time of operation of the motor.
However, currently, keeping pace with capacity increase of the washing machine, though it is required to increase an output of the motor for rotating the drum too, such an increased output of the motor requires large sized rotor and stator, to increase size and weight of the motor, significantly.
Consequently, the increase of the motor size causes to increase a size of the washing machine or the like having the motor applied thereto, significantly.
Accordingly, a motor is required, which increases an output of the motor without increasing a size of die related art motor.